Structure and method for protecting a passenger during a crash
A method and apparatus for protecting a passenger during a crash comprises a moveable seat with an energy absorber (EA) that allows the seat to stroke a finite distance to decelerate the passenger in a controlled manner. The seat is designed so that one of a plurality of fixed profile EA's can be selectively engaged to provide a tailored EA composite profile adapted to the occupant's weight and anticipated crash environment. The tailored EA composite profile applies a frequency matched, low onset force to the seat, which substantially eliminates problems associated with dynamic overshoot of the passenger's spine.
1. A method for minimizing injury to an occupant of a vehicle having a seat, the method comprising:
providing an energy absorbing apparatus operatively connected between the seat and the vehicle, the energy absorbing apparatus comprising a plurality of Fixed Profile Energy Absorbers (FPEAs);
determining an anticipated impact loading of the occupant;
determining an absorption energy necessary to prevent injury to the occupant based on the anticipated impact loading and the occupant's mass; and
prior to an impact, selectively coupling at least one of said plurality of Fixed Profile Energy Absorbers between the seat and the vehicle to provide a predetermined force versus stroke profile that will absorb the energy necessary to prevent injury to the occupant, whereby selectively coupling at least one of said plurality of Fixed Profile Energy Absorbers provides a variable force versus stroke profile simulating a Variable Profile Energy Absorber providing a frequency matched force on the occupant, whereby a lumbar load spike is avoided.
2. The method of claim 1 , wherein:
plural of said plurality of Fixed Profile Energy Absorbers have equal work increments.
3. The method of claim 1 , wherein:
plural of said plurality of Fixed Profile Energy Absorbers have unequal work increments.
4. The method of claim 1 , wherein:
plural of said plurality of Fixed Profile Energy Absorbers have a predetermined load versus stroke profile that is piecewise linear in shape.
5. The method of claim 1 , wherein:
each of said Fixed Profile Energy Absorbers has a fixed energy profile having an energy absorption value and the step of selectively coupling at least one of said plurality of Fixed Profile Energy Absorbers between the seat and the vehicle comprises selecting a lowest energy absorption value that is greater than the absorption energy necessary to prevent injury to the occupant.
6. The method of claim 1 , wherein:
at least one of said plurality of Fixed Profile Energy Absorbers provide a decelerating force on the occupant that varies with stroke distance.
7. The method of claim 6 , wherein:
the vehicle comprises a helicopter and the vehicle control system comprises an avionics system of the helicopter.
8. The method of claim 1 , wherein:
the step of determining an anticipated impact load on the occupant comprises receiving information from vehicle-borne sensors.
9. The method of claim 1 , wherein:
the step of determining an anticipated impact load on the occupant comprises receiving information from a vehicle control system.
10. The method of claim 1 , wherein:
plural of said plurality of Fixed Profile Energy Absorbers comprise tubes having variable wall thicknesses.
11. The method of claim 10 , wherein:
plural of said plurality of Fixed Profile Energy Absorbers comprise aluminum tubes.